Fix reasoning/content separation and eliminate empty message divs

- Remove extractReasoningMiddleware as it expects <think> tags but API sends reasoning fields directly
- Ensure reasoning and content tokens create separate assistant messages
- Filter empty assistant messages at conversation level to prevent empty divs
- Add deduplication for tool results to prevent duplicates
- Only render content div when message has actual content

examples/chat-ui/src/components/ChatMessage.tsx

@@ -48,19 +48,22 @@ const ChatMessage: React.FC<ChatMessageProps> = ({
           />
         )}
         
-        <div className="prose prose-zinc">
-          <ReactMarkdown
-            remarkPlugins={[remarkGfm]}
-            rehypePlugins={[rehypeHighlight]}
-            components={{
-              table: ({ children }) => (
-                <div className="overflow-x-scroll text-sm">{children}</div>
-              ),
-            }}
-          >
-            {message.content}
-          </ReactMarkdown>
-        </div>
+        {/* Only render content div if there's actual content */}
+        {message.content && message.content.trim() && (
+          <div className="prose prose-zinc">
+            <ReactMarkdown
+              remarkPlugins={[remarkGfm]}
+              rehypePlugins={[rehypeHighlight]}
+              components={{
+                table: ({ children }) => (
+                  <div className="overflow-x-scroll text-sm">{children}</div>
+                ),
+              }}
+            >
+              {message.content}
+            </ReactMarkdown>
+          </div>
+        )}
       </div>
     </div>
   );